This section of this document is intended to introduce various aspects of art that may be related to various aspects of the present invention described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the present invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
The present disclosure relates to systems and methods for deploying and/or retrieving equipment towed from a marine vessel and more particularly is related to deployment and retrieval systems and methods for seismic survey vessels.
Seismic exploration involves surveying subterranean geological formations, for example for hydrocarbon deposits. A survey typically involves deploying seismic source(s) and seismic sensors. The sources generate seismic waves, which propagate into the geological formations creating pressure changes and vibrations along their way. Changes in elastic properties of the geological formation scatter the seismic waves, changing their direction of propagation and other properties. Part of the energy emitted by the sources reaches the seismic sensors. Some seismic sensors are sensitive to pressure changes (hydrophones), others to particle motion (e.g., geophones), and industrial surveys may deploy only one type of sensors or both. In response to the detected seismic events, the sensors generate electrical signals to produce seismic data. Analysis of the seismic data can then indicate the presence or absence of probable locations of hydrocarbon deposits.
Some surveys are known as “marine” surveys because they are conducted in marine environments. However, “marine” surveys may be conducted not only in saltwater environments, but also in fresh and brackish waters. In one type of marine survey, called a “towed-array” survey, an array of seismic sensor-containing streamers and/or sources is towed behind a survey vessel. The seismic sources are commonly referred to as source arrays and include one or more energy sources (e.g., acoustic source, electromagnetic source) such as an airgun. The source arrays may be towed behind a marine vessel that also tows the streamers and/or from a dedicated vessel (e.g., source vessel). The source arrays may be deployed and/or towed in various manners included stacked arrays and spread arrays.
The tow vessel typically includes a deck designed for storing and handling the seismic gun cables and detection cables or streamer cables, which constitute the means whereby the seismic surveys are performed. The source arrays and/or streamers are commonly transported to a slip area from the storage area of the vessel for deploying into the water and the source arrays and streamers are retrieved from the water at the from the slip area of the vessel and then transported to the storage area.
In regard to the source arrays, it is typical for various manual operations to be performed in the slip area in order to deploy and to retrieve the source arrays. For example, various source array equipment such as the gun assembly, floats, etc. may be transported into the slip area via a device referred to generally as a trolley. Often, the trolley is provided via a rail into the slip area. Inside of the slip area and often at the slipway (e.g., opening to the water) personnel disconnect, for example, the gun assemblies from their transporting trolleys so that the gun assembly may be introduced into the water on its tow cable. It is common for the gun assemblies to weigh at least 0.5 tons. Similarly, when retrieving the source arrays manual operations are required in the slip area and in dangerous proximity to the water, for example, connecting the retrieved gun assemblies to trolleys for movement back into the slip area and ultimately into the storage area.
A seismic source handling system, according to one or more aspects of the present disclosure, for deploying and/or retrieving a seismic source array having a gun assembly from a marine vessel may include a tow winch disposed on the vessel capable of deploying and/or retrieving a tow member connected to the source array; an elevated handling beam extending from an inboard position to an outboard position proximate to an open slipway; and a beam winch moveably disposed on the handling beam, the beam winch selectively connectable to the gun assembly.
A method, according to one or more aspects of the present disclosure, for deploying and/or retrieving a seismic source array from a marine vessel having a slip with an open slipway to the water may include locating a gun assembly proximate to the slip at a position distal from the slipway; elevating the gun assembly; moving the gun assembly laterally to a position proximate to the slipway; and deploying the gun assembly into the water.
Another method, according to one or more aspects of the present disclosure, includes positioning an elevated handling beam in a slip of a marine vessel, the handling beam extending from an inboard position to a outboard positioned proximate to an open slipway; and moveably positioning a handling winch on the handling beam, the handling winch capable of selectively connecting with a gun assembly and moving the gun assembly vertically and laterally relative to the handling beam.